This invention relates to spectral normalizers and more particularly to a wide dynamic range post-processing digital normalizer.
Various types of displays employing means for varying the intensity to denote various levels in the amplitude of signals are referred to as intensity modulated displays (IMD). However, it is not possible to maintain the recognition differential necessary for spectral detection over a large dynamic range on an intensity modulated display without employing a means of normalizing. This is due to the presence of noise signals of variable intensity in different parts of the frequency spectrum. As an example, it has been found that the resolution of the frequency spectrum at an intensity modulated display (IMD) is limited to about eight shades of gray, ranging from black to white, which are discernible by a naked eye. When it is necessary to maintain recognition differential using only eight gray levels, the dynamic range between insufficient signal strength corresponding to the white color region and to the overloaded signal strength corresponding to the black color region is limited. It is thus desirable to employ means which make it possible to maintain recognization differential while displaying spectral signals of a large dynamic range on an IMD.